Exegesis:

estin de hautē hē parabolē ‘now the parable is, or, means this.’ hautē is predicate.

ho sporos estin ho logos tou theou ‘the seed is the word of God.’ ho sporos is subject. estin is best understood in the sense of ‘stands for.’ For ho logos tou theou cf. on 5.1.

Translation:

The parable is this, or, ‘means this.’ The rendering should preferably parallel the one used in v. 9.

The seed is the word of God, or as a simile, ‘the seed is as/to-be-likened-to the word of God’ (Low Malay). For the word of God see on 5.1.

Quoted with permission from Reiling, J. and Swellengrebel, J.L. A Handbook on the Gospel of Luke. (UBS Handbook Series). New York: UBS, 1971. For this and other handbooks for translators see here . Make sure to also consult the Handbook on the Gospel of Mark for parallel or similar verses.